of geneva



Reis'sued Sept. 8, 1931 UNITED STATES PATENT OFFICE MARCEL LEVY, OFGENEVA, SWITZERLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, TO PBODOBITE S. A.,OF GENEVA, SWITZERLAND MANUFACTURE OF CONCRETE No Drawing. Original No.1,699,705, dated January 22, 1929, Serial No. 598,651, filed November 2,1922.

' Application for reissue filed October 3, 1930. Serial No. 486,277.

Reinforced and non reinforced concretes hitherto used for theconstruction of pipe lines, containers for liquids and hydraulicstructures of all kinds consist, as is known, of a mixture of pebbles,broken stones, sand and similar filling materials on the one hand andcement, lime, silicates and other mineral salts on the other hand, whichare mixed with a definite quantit of water and yield a product thatbecomes hard after a certain time.

The present invention in brief consists in a method of manufacturing aconcrete having mechanical properties similar to cement concrete andretaining these properties under temperature conditions of use whichcomprises the incorporation under the action of heat of a selected orspecially prepared hard pitch with graded filling materials, namely,materials of large size, for example coarse broken stone, fine material,for example powdered stone, and intermediate material, for example sandor gravel.

The improved concrete forming the subject of the'present inventionpossesses considerable and numerous advantages in comparison with theconcretes hitherto known, for example it is possible for the first timeto produce reinforced and non-reinforced concretes, which in themselvesand without the use of any coating can resist the action of chemicalsubstances and in particular acids and even concentrated acids.

Further these concretes can be produced with rather smooth surfaceswhich are impermeable towater even ata pressure above 15 atmospheres,without the use of any coating.

Concretes produced in this manner are at least as strong as the usualcement concrete.

Three samples each were tested at a temperature of 20 and C. and gavethe following results Bending stress ex- Crushing pressed in st kg. persq. kgjcm.

No. 1. 65. 9 420 No. 2 at 20 C 73. 4 400 No. 3 69. 88 390 0. 4 62. 5 387No. 5 at 60 C- 70. 4 391 o. 6 66. 5 407 It may be here remarked that themanufacture of compositions with graded or voidless aggregates is wellknown and the use of pitch as a binder is well known.

Further, pitches of various degrees, of hardness are available or havebeen proposed.

In almost every case, however, for present commercial requirements thepitch to be employed, although it may be hard pitch, is yet as regardsthe present invention comparatively soft.

I have found it necessary when pitch is to be incorporated as a bindingmaterial for the purpose of obtaining the benefit of the presentinvention to employ a pitch which is harder than the ordinary pitches,such for instance as a pitch which is heated to about 350 C. for drivingoff the constituents volatile at that temperature. Such a pitch whentested at the maximum temperature of use, say with the Brinell machinewith a ball of 20 mm. and a load of 100- kgs., should not give a readingbelow 10 as the Brinell hardness figure and preferably not less than 15and its softening point as indicated by a rapid decrease in the Brinellhardness figure should not occur'below about 40 C. or some highertemperature according to the use to which the composition is to be put;otherwise a composition having mechanical properties at the temperatureof use similar to cement concrete cannot be obtained. A

A method of producing such'a concrete will now be given by way ofexample.

In order to produce a cubic metre of concrete, we heat to the meltingpoint for example from 250 to 350 kgs. colophony, sulphur, gum resin orsimilar products, gas pitch, it being essential that the product usedremains very hard at the temperatures to which the concrete may besubjected in use. To the liquid mass are added at about 200 C. 1700 kgs.of broken stone and about 700 kgs. limestone powder and heat appliedwhilst stirring constantly. The homogeneous mass obtained is cast as forordinary cement concrete in the hot condition into moulds or shells andsets on cooling. and forms a structure of great strength, which 'der andthen to add the may even exceed that ofordinary cement concrete.

. The improved concrete may also be produced in another Way. Forexample, coarse grained filling material such as broken stone are firstheated to about 200 C. and added to the mixture of the organic bindingagent and sand; or the binding agent may first be mixed with the powderand then the coarse grained material added. It is also possible first toheat the broken stone, sand and powpitch in powder form.

It'is essential that the binding agent should be quite hard at thetemperature to which the concrete is to be subsequently exposed; aresult of this is that the softening temperature of the binding agentforms an important factor; as upon this depends the temperature to whichthe concrete may be heated without losing its strength. For this reasonthe pitch binding agent, according to the circumstances, may besubjected to a special treatment in order to increase its softeningtemperature. It is known, for example,- that the softening temperatureof the various kinds of pitch can be increased by treatment with limeand that of tar distillation products by conducting a current of hot airthrough the mass at the end of the distillation, the air removing thereadily volatile constituents.

It is also known that by treating pitch with hydrochloric or sul huricacid, the softening temperature of t lis substance is in creased. Pitchmay also be subjected to a preliminary treatment in order to purify itand particularly to remove therefrom the soluble substances which it maycontain. For this purpose it may be washed with cold or hot water orwith cold or hot solutions of mineral acids or soda. In order to renderthe pitch entirely acid-resistant, it may also be previously treatedwith concentrated mineral acids and then washed with flowing water, butwhatever preliminary treatment be given in the way of washing with wateror acids, if the pitch is not hard enough according to the tests givenabove it must be made sufiiciently'hard, for example, by heat. Asuitable pitch for use in my concrete is gas pitch, mineral oil pitch,or an other pitch of inferior or cheap quality w ich remains hard inwater at C. In order to determine the hardness a sheet 1- mm. thick ofthis pitch is placed in hot water and heated for some minutes. The sheetshould remain quite hard and should not be pliant or scratched by thefinger-nail.

Instead of broken limestone all kinds of broken stone, broken bricks ortiles, lava, stoneware, granite, quartz, cork, coke, coal, slag, gravelin fact any solid rubble material and so forth may be used. Brokenminerals with sharp edges and rough surfaces give stronger concrete thangravel with smooth surfaces. The limestone powder may also be replacedby other still more finely powdered substances such as clay, stoneware,pumice stone, graphite, coal, soot, kieselguhr, very fine sand and soforth or any other inert powder. I

The choice of coarse and fine granular constituents for the new concreteis of great importance.

' For instance with hard non-porous limestone in broken up andpulverulent condition 250 kgs. hard gas pitch are required for one cubicmetre of concrete, whereas with porous, soft limestone which can be sawnabout 400 kgs. are required and with broken pumice stone and pulverizedkieselguhr about 500 kgs. of hard gas pitch are necessary. From this itwill be seen that the relative proportions of the constituents alsodepend upon the composition of the mixtures. Care must however be takenthat with the coarse granular material sufiicient finely powderedsubstances are mixedin order to obtain a thick pasty mass in which thecoarse stones remain in suspension andare uniformly distributed.

In order to prevent contraction of the concrete when setting as muchcoarse granular and pulverized filling material as possible is used.

The improved concrete according to the present invention must not beconfused with the mixtures containing tar which are used for coatingroads, pavements or roofs or also for engine foundations. These mixturesnecessarily must be more or less soft, plastic and resilient and cannotbe used in building constructions in place of ordinary cement concretefor the construction of large containers, water pipes, high pressurepipes (up to 20 atmospheres) dams, dykes, subaqueous structures and soforth.

Asphalt pipes are already in existence which are constructed of cement,iron, glass or wood and then coated either externally or internally withartificial or natural asphalt or asphalt or tar pulp, which are rolledtogether a number of times, to form a pipe which actually is composed oflayers of pulp and asphalt or tar.

These facts assist in bringing out the feature of the present inventionstill more as here the natural or artificial asphalts, by reason oftheir presence, do not offer much resistance but are pliable andplastic, so that in an unhardened condition they cannotbo used in themanufacture of pipes as they are not sufliciently strong; for thisreason it is necessary to reinforce them with wood, cement concrete,glass or pulp. The only kinds of pitch which at present are able to besold are pitches which are not extremely hard.

For this reason pitch which is produced as a. hard pitch before it isplaced on the market is softened by the addition of oils. The pitchwhich is required for the present invenpipe which has been produced bymeans of gas tar the distillation of which has been carried through to asufficient extent in order to obtain a pitch which is very hard andremains hard at temperatures of 80 C. and over.

With this very hard pitch, which is very j brittle and shiny, there isobtained when it is melted and mixed with broken stone, sand and stonepowder, a concrete which when cast into pipe moulds, 30 cm. in diameter,4 cm. thick and 1 meter long, pipes are formed for the fracture of whicha load of more than 3500 kgs. is necessary and this at temperatures of20 and 60 (1, the pipe being loaded on its upper part along a length of50 cm.

For an aged ordinary cement pipe which was cast in the same mould asthat which was used for the new concrete, i. e. which had exactly thesame dimensions and subjected to loading under the same conditions only2500 kgs. were necessary to produce the fracture.

From this will at once be seen the importance of the new concrete forthe construction of pipe linesof all descriptions as the pipes can beproduced at almost the same price as ordinary cement pipes, whilst thepipes of the new concrete are stronger, more resistant against chemicalaction and at the same time are'impermeable to water and possess verysmooth surfaces.

There are a number of patents in existence for converting tar containingbituminous substances into'artificial asphalt. In all these patentsendeavours are made to' give these products the properties of asphalts.These must be soft and plastic and therefore vary their hardness insummer and winter in an appreciable manner. To the natural asphalticearths there is always added a certain quantity of very soft bitumenwhen the cast, asphalt, is being prepared so that it does not crack inthe cold.

Owing to the fact that natural or artificial asphalts are soft andplastic they cannot without hardening be used for the preparation ofconcrete, for the construction of pipe lines, containers of allkinds-and similar structures.

In order to illustrate the above better, experiments were made for theproduction of concrete for the construction of pipe lines and so forthwith different asphalts especially Seyssel asphalt, as used for theproduction of cast asphalt slabs. These concretes were prepared asfollows The asphalt was melted, then mixed with broken stone in order toobtain a thoroughly uniform mixture in which the stones could no longersink. This concrete is thus similar to that used for the production ofroad paving. A number of square plates 36 x 12 cm. were produced-whichwere tested as regards bending and pressure. The following are theresults obtained by thesetests Bending stress ex- Crushing pressed instress kg. per kg./cm.

No. 3141 at 20 16. 7 31 N0. 310 at 40 5. 7 15 same asphalt concrete andhaving a diame ter of 30 cm. a length of 1' m. and a thickness of 4 cm.;at a temperature of 25 C. this collapsed under a small-load.

Asphalts can be used for the production of the new concrete according tothe present invention but they must be previously treated in order thatthey may be hardened, so that at a temperature to which the concrete maybe exposed later they are hard: i. e. the asphalts will no longerpossess properties peculiar to asphalts and can no longer be used forcoatin roads and so forth.

Hard pitch which is suitable for the present invention, cannot replaceasphalt as it is .too friable, will crack too easily and cannot be usedfor coating roads.

' The presence of coarse gravel, or better of broken stone, plays a "cryimportant part in the preparation of the new concrete.

As a general rule it is possible to say that: (1)- the more compact thestructure of the solid body the smaller will be the quantity of pitchrequired; (2) the greater the proportion of the solid body in thefilling material, the smaller will be the liability of the concrete tocrack.

In order to facilitate the combination of an old pitch concrete with anew one the surface of the old concrete may be coated with a varnish orsimply with tar or a thin layer of soft asphalt may be poured betweenthe old and the new concrete, whilst the latter is still hot andviscous. This can be done in the following manner:

The new still viscous and soft layer of concrete is separated from theold layer by a trowel and asphalt is poured into the small interveningspace. In this-manner an effective combination is obtained between thetwo layers whilst the connecting layer is at the same time also elastic.

The following are a few examples for precording to the presentinvention:

500 kgs. of hard pitch which remains hard Further a pipe was constructedfrom the paring compositions for particular uses ac at about 80 C. areheated to the melting point and mixed, whilst continuously heating andstirring, with 1200 kgs. broken stoneware or pieces of burnt clay orquartz, of which the separate pieces have a thickness of from 1 to 30mm. as obtained from the stone crusher. In order to prevent these largepieces from sinking in the mass very fine powdered stoneware is addedduring the continued heating so that the mass becomes thick and pastyand the coarse granular solid constituents remain in suspension. As soonas the mass becomes so thick that the solid constituents no longerseparate from the liquid parts it is poured whilst still hot into metallined wooden shells or moulds in exactly the same manner as when makingordinary cement concrete.

If it is desired to produce reinforced concrete then the ironreinforcements are arranged in the same manner as for ordinaryferro-concrete.

With the new concrete it is possible to construct containers of anydesired capacity,

pipelines and the like which will resist the action of acids andespecially concentrated hydrochloric acid so that even after being inuse for many months they do not show the least signs of decay.

Instead of broken stoneware, lava, pumice stone, quartz and so forth maybe used which will resist acids. The powdered stoneware also-may bereplaced by kieselguhr, pumice stone powder and the like.

The new concrete resists frost and refrigeration as also changes oftemperature. A beam constructed of the above concrete 2 m. in length and10 cm. wide was exposed for some days in a freezing chamber at atemperature of 14 C. after which it was placed in hot water above 40 0.,the beam resisted this change of temperature without any injury. Afurther test was made with a piece of concrete. which was completelycovered with ice. This piece was then exposed to the action of. steamfor melting the lee and was not damaged by this treatment.

The new concrete may also be used as a .lining for containers of cementconcrete.

For this purpose a layer of pitch concrete is poured on the cement to athickness of a few centimeters, so as to .cover the whole inner surfaceof the container. The new concrete adheres very firmly to the cementconcrete; a

container constructed in this manner was in use for many months withoutany cracks being observed. This tank was about three feet deep and threefeet indiameter. In the case of large containers joints may be employedbetween sections of the lining by leaving gaps and filling them with aplastic material, for example asphalt.

In order to obtain quite smooth surfaces which are even smoother thanthose of glazed earthenware and which is of great importenginefoundations.

ance in the case of pipes, the new concrete is poured into previouslyheated moulds or shells provided with smooth surfaces. In the case ofwooden shells or moulds polished wood may be .employed or better stillwood covered with sheet iron or the like.

The new concrete has nothing in common with tar products which are usedfor coating or paving roads, pavements or roofs or for These productsmust usually be comparatively soft and elastic and cannot be used inplace of ordinary cement concrete in building construction and for theconstruction of dams, dykes, large containers, and high pressure waterpipes up to 20 atmospheres.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is 1. As a new article of manufacture, a pitchconcrete having mechanical strength substantially equal to that ofcement concrete, comprising a brittle pitch dried so as to remain hardat temperatures of 80 (1., said concrete also containing an aggregateand a substantial portion of fine powder sufiicient to form a thickpasty mass with the pitch ingredient.

2. A bituminous concrete consisting of a pitch binder which is hardand'brittle at ordinary temperature and remains so hard at a temperatureof (J. that a sheet one millimeter thick is not pliant nor is the binderindentable by the finger nail at such temperature, coating and joiningparticles of fine mineral powder in, quantity at least twice the weightof the binder, and particles of graded aggregate in a quantity of morethan twice the weight of the powder.

3. A composition of matter comprising a graded mineral aggregate andcontaining a substantial proportion of fine mineral powder, to which atar pitch has been added in a proportion smaller than 18 percent of thecomposition, which pitch is hard and brittle at ordinary temperaturesand when placed in I water at 70 C. in a sheet one millimeter thickremains hard and is not pliant nor can it be indentable by the fingernail, the quantity of powder being substantially greater than that ofpitch, and the quantity of aggregate being substantially greater thanthat of powder,-so that the composition has a resistance to crushingstress not less than that of cement concrete over a temperature range upto 60 C.

4. A composition of matter comprising an aggregate and fine mineralpowder substantially filling the voids of the aggregate, and a tar pitchbinder which is hard and brittle at ordinary temperatures and retainsits hardness to a temperature of 70 C. but I combined aggregate andpowder, said composition at temperatures between 20 and 60 C. having aresistance to crushing stress of substantially 387 kilograms per squarecentimeter. I

In testimony whereof I have signed my name to this specification.

MARCEL LEVY.

